Honestly right now, this mess is made from the author's lack of focus. Initially she was intending to develop Siwon's character, the dying Jinha was supposed to be Siwon's saving grace, but then the author suddenly stumped his growth by introducing a more eye-catching character which is Xuan. The one wrong of the author is that she didnt give Siwon's hesitancy a strong background plus she didn't let their relationsgip progress deeper. That's why a lot of you feel that Xuan and Jinha could be better because Siwon and Jinha's relationship didnt manage to stick in your minds. Honestly, I was really angry at first why a lot of people didnt understand where Siwon was coming from, but I realized that not much was given emphasis on his character despite him being the MC. The author seriously needs to care for his main characters more than his side ones.
I really appreciate Jin-woo. He's badass and amazing but his personality is attractive. After dropping so many isekai and xianxia novels because of the typical arrogant and harem building protags, he feels like a breath of fresh air. I especially liked the part when he asked for permission from kihoon even through he is stronger. He respects people no matter their strength and he does not hesitate to help. The other charas are well written too. Most of them are relatable.